Final TBM breakthrough for KAT2 at Koralm 23 Aug 2018

TunnelTalk reporting

After launch in March 2013, the second of two 9.93m diameter TBMs working on the 18km long main running tunnels of the KAT2 contract for the Koralm rail tunnel in Austria broke through on Tuesday 14 August to finalise TBM excavation for the Strabag/Jäger Bau JV.

The two KAT2 TBMs were assembled, launched and operated from the bottom of 60m deep working shafts

The KAT2 Aker Wirth machines progress from Leibenfeld in the north

The twin Aker Wirth telescopic shield TBM in the parallel running tunnel completed its 18km long drive in February 2018.

As the TBMs progressed, the tunnels were lined with a precast concrete segmental lining and muck was removed to the surface via continuous conveyor systems supplied by Agir of Switzerland. Both machines were launched and services from the bottom of 60m deep working and access shafts.

A Herrenknecht TBM is working on the drives from the south

Breakthrough of the second TBM took place in an underground cavern constructed as part of the KAT3 tunnelling contract being progressed by Austrian contractor Porr. The KAT3 contract for the southern section of the 33km long twin tube Koralm tunnel comprises about 16km of twin tube excavation through varying geological conditions including across the Lavanttal fault zone. For excavation Porr is using both conventional drill+blast excavation and a 9.9m diameter dual hard rock/soft ground Herrenknecht TBM, which has about 6km to complete before breaking through into the same mid-tunnel breakthrough cavern.

The 33km long twin tube Koralm tunnel, passing through the Koralpe mountain range to a maximum overburden of 1,200m and for a total of 66km of excavation, is a key element in the Baltic-Adriatic rail corridor. The route is scheduled to be opened to traffic in December 2025. Once in service, the 130km journey between Graz and Klagenfurt, passign through 47km of tunnel, including the 33km long Koralm tunnel, will be reduced to 45 minutes in trains travelling at speeds of up to 250km/hr.

Aker Wirth News Release

Aker Wirth has secured one of the highly prized TBM orders of the moment. Two Aker Wirth TBMs are ordered by Strabag for excavation of its main construction lot KAT 2 contract for the Koralm high-speed railway tunnel project in Austria.

The 32.5km Koralm tunnel, a vital part of trans-Austrian and inter-European rail services

The two telescopic shield TBMs will work on the 20km long heart of the 32.5km long Koralm tunnel on the new high-speed rail route between Graz and Klagenfurt. The two 9.93m diameter TBMs will be in operation from October 2012 and will operate through a 60m deep shaft as the only access to the underground construction work. This brings a particular challenge to the construction process.

Christoph Kleuters, CEO of Aker Wirth, said: "Winning this major European project has filled us with pride. We strengthen our technological leadership continually, particular in hard rock TBM technology. Whenever high technology is required, we deliver the tunnel boring machine - something we have been doing for the last 40 years. We convince our customers not only with our approach to machine design but also with our comprehensive and professional consulting and on-site service."

Wolfgang Lehner, General Manager at Strabag AG, explained: "Aker Wirth, in cooperation with Rowa Tunnelling Logistics AG, emerged victorious as the best candidate from a tender procedure carried out by us. The technical solution to the task along with expertise in hard rock TBMs convinced us, as well as the cost-effectiveness of the tender. We are confident that we have found the right partner to meet the challenges of this exceptional project."

The two telescopic shield machines can be identified by the typical Aker Wirth wing-type gripping system in the rear sections of the shield. This provides optimal support via the secure three-point bearing to produce high-performance boring with very little vibration. The cutter head is driven by electric motors with an overall power rating of 4,800kW and a maximum cutting torque of 30,000kNm. The back-up will be designed and delivered by long-standing cooperation partner Rowa Tunnelling Logistics of Switzerland. The entire tunnelling system is approximately 160m long and weighs in excess of 1,800 tonne. The manufacture of each machine will take around a year and the first machine will start tunnelling in October 2012.

With the new high-speed rail route and its long Koralm tunnel, ÖBB Austrian railways will provide reduce travel times between Graz and Klagenfurt by half. This 130km long key link is part of the Baltic-Adriatic Axis from Eastern Europe to Northern Italy via Austria. The Koralm tunnel, with two parallel single-track tunnel tubes and a length of more than 30km, is the core of this railway line and will be one of the longest traffic tunnels in the world.

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